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Two short (100 and 175 cm-long) sediment cores from the southwestern corner of Lake Urmia provide a record of vegetation dynamics, lake-level changes and the role of climate and humans in shaping the landscape around Lake Urmia over the last 2550 years. Relatively low values of arboreal pollen (AP), and substantial values of Artemisia pollen from 2550 to 1500 cal BP indicate the prevalence of steppe vegetation and relatively arid climate in the area. However, a prominent peak of Riella spores may indicate a short-lived lake-level rise for the period 1900–2000 cal BP. The next period, 1500–550 cal BP, is characterized by substantial rise in AP, particularly Quercus , and a sharp decline of Artemisia , Chenopodiaceae/Amaranthaceae and wetland pollen types, suggesting the expansion of oak forests under a rather moist climate and/or a decline in agro-sylvo-pastoral practices in the area. Agricultural activity in the area can be inferred from sporadic occurrences of Vitis , Ricinus and Juglans pollen from the beginning of the record. The rise of saline habitat pollen types between 1100 and 800 cal BP, along with increased values of magnetic susceptibility and organic matter, suggest a lower water level and the subaerial exposure of saline mud flats, which could favour the re-colonization of chenopods and other halophytes around the margins of the lake. Thus, the Medieval Climatic Anomaly seems to be warmer-than-present in the Lake Urmia region. From 450 to 150 cal BP, the decline in Quercus and high values of Artemisia , along with higher lake levels and high magnetic susceptibility values, could be associated with the Little Ice Age. Since 500 cal BP, Quercus and Riella steadily decline and fade out towards the surface of the core, whereas pollen types attributable to steppe and desert vegetation increase. A prominent increase in organic matter in the uppermost part of the record could be associated with a lower lake level and the expansion of wetland vegetation in the recent past. Our findings suggest that the regional forest coverage in the highlands of Zagros and Azerbaijan has reached its minimum during recent decades, while Urmia's lake level dropped dramatically (increasing its water salinity) most likely as a function of extensive anthropogenic activities and general climate aridification. [ABSTRACT FROM AUTHOR]

Pollen analysis and radiocarbon dating of a core from northern Iran enable reconstructing the past three millennia of vegetation dynamics of the Caspian lowlands and Alborz foothills of central northern Iran as a function of Caspian Sea level oscillations, climate change and human impact. The high values of Alnus pollen and a diverse assemblage of non-pollen palynomorphs indicate that during most of the time span covered by the record a wet eutrophic to mesotrophic alder ( Alnus cf. glutinosa ) carr was present at the coring site. Only at the onset of the 2600-BP highstand event tree growth was hampered because of inundation. Our findings (including calcareous gyttja with remains of Charophytes; remnants of molluscs, freshwater snails, Foraminifera, Ostracoda, Algae and sponges) indicate that the highstand extended to and culminated in the period 2100 to 1900 calBP. Wingnut ( Pterocarya fraxinifolia ), which was a major component in the vegetation composition of the Caspian lowland from the beginning of the record, strongly decreased after ca. 1200 calBP, most probably due to a drier or colder climate. Artemisia and Chenopodiaceae and Amaranthaceae (C-A) show fluctuating and largely parallel values throughout the record, suggesting the natural co-occurrence and similar ecology of their corresponding plants in the coastal areas under the influence of Caspian Sea transgressions. The steep slopes south of the mire were probably most of the time covered by a species-rich deciduous forest predominated by hornbeam ( Carpinus betulus ) and beech ( Fagus orientalis ) accompanied by oak ( Quercus castaneifolia ), elms ( Ulmus glabra / U. carpinifolia ), Persian ironwood ( Parrotia persica ), maples ( Acer velutinum / A . cappadocicum ), box tree ( Buxus hyrcana ), grape ( Vitis vinifera ), ash ( Fraxinus excelsior ), and lime ( Tilia platyphyllos ). However, climate change and human impact triggered significant vegetational changes both in the lowland and the hilly upland. The first signal of human activity in the area can be inferred from findings of pollen of Juglans regia at ca. 2350 calBP and slightly later of Fagopyrum esculentum . A dramatic decline of tree pollen over the last centuries suggests that tree cover of both the lowland and upland landscape surrounding the mire declined and forests were increasingly replaced by open vegetation most likely as a result of intensified human activities. [ABSTRACT FROM AUTHOR]

Pollen analysis of the peat in a small mire on the northern slope of the Alborz Mountains (550 m a.s.l.) in the Central Caspian forests of Iran reveals changes in forest and wetland vegetation during the last millennium.A forest, principally of Alnus and Carpinus occurred over almost the whole period. Quercus, Ulmus and Parrotia were less common, while Fagus, Pterocarya, Acer and Diospyros fluctuated as a probable result of human interference and/or climatic change. Two phases of clay deposition in the mire can be dated to the 'Mediaeval Climatic Anomaly' (AD 1100) and the beginning of the 'Little Ice Age' (AD 1560-1600). Although human activity seems to have persisted in the region during the whole of the past millennium, increased NAP values point to intensified human interference since the beginning of the nineteenth century. [ABSTRACT FROM AUTHOR]